This invention relates generally to the field of wireline tools used for subsurface earth formation testing, and more particularly to wireline tools used for determining the bubble point pressure of fluid flowing from a subsurface formation.
Electric wireline tools are used for determining bubble point pressure of fluid originating from a subsurface earth formation in order to determine properties of the fluid used in calculating the total fluid content within the formation. One of the methods of determining in situ bubble point pressure of formation fluid involve the use of downhole electric wireline tools capable of withdrawing a sample of fluid from a subsurface earth formation into a sample chamber and incrementally expanding the volume of the sample chamber while measuring the pressure. The bubble point pressure of the fluid is then extracted from a plot of the pressure versus volume data. These conventional tools are used only in the exploration stage, are not useable during well production, and are removed from the wellbore prior to flowing the well.
Other conventional methods of determining bubble point pressure of a formation fluid involve withdrawing a sample of fluid from the earth formation into a chamber of a testing tool. Then, the bubble point pressure measurement is done at the well site or laboratory by measuring the pressure and volume of the sample, while expanding the volume of the sample. Such conventional tools are not permanently installed, and do not permit the determination of in situ fluid bubble point pressure during well production.
Conventional methods and apparatus for remotely controlling well production employ the use of various downhole electromechanical devices coupled with computer based surface systems. One such device is an adjustable choke with pressure sensors located upstream and downstream of the choke for attaining desired wellbore pressure by controlling fluid flow during the life of the well. However, such devices do not use the adjustable choke in determining a bubble point pressure of the fluid.
Therefore, a need exists for a method for determining fluid bubble point pressure during well production.
The present invention is directed to overcoming one or more of the limitations of the existing devices.